1. Field of the Invention
This invention relates to the dissolving of non-ferrous metal, and more particularly to new and improved compositions for dissolving non-ferrous metal. Additionally this invention relates to a process for the dissolution of non-ferrous metal.
2. Description of the Prior Art
Stripping solutions are known in the prior art which consist of an aqueous solution of ammonium persulfate and ammonium carbonate. Although such stripping solutions are satisfactory in certain respects, they suffer from having a low capacity for copper and having a tendency to go "dead" when only about 2-8 oz./gal. of copper has passed into solution and usually when about 4 oz./gal. of copper has been dissolved. By the solution going "dead" as the term is used herein is meant the stripping rate becomes so low that it is impractical to use the solution any further for stripping or dissolving the metal, and the solution is dumped to the sewer. Further such prior stripping solutions have a non-uniform stripping rate, and the ammonium persulfate is unstable and tends to decompose in the solution.
Nitric acid is known to be a good stripper for copper, but it is disadvantageous for stripping copper from ferrous metal, for instance steel, as the nitric acid is not selective for the copper and also attacks the steel. The nitric acid also evolves dense, noxious fumes when dissolving copper.